This invention generally relates to medicators for use in surgical and related procedures and more specifically to apparatus for the administration of beneficial parenteral liquids, such as blood, saline solutions and the like.
These liquids are sometimes stored in glass bottles. To administer such liquids, the bottle is placed above the patient on a hanger so the liquid flows to the patient by means of gravity. However, such bottles are heavy and bulky. They are difficult to handle and subject to breakage. As a result, it has become more desirable in recent years to store such liquids in and administer such liquids from deformable plastic containers. These containers are usually formed of a plastic film, such as a polyvinylchloride film, and usually are equipped with ancillary tubes to adapt them to the particular purpose for which they are intended.
Recently it has been found advantageous to administer such liquids under pressure. Although a number of arrangements for supplying liquids under pressure have been proposed, many have not gained any commercial acceptance.
In accordance with one such proposal, a container comprises a first deformable bag for storing a liquid. This first bag is located within a second deformable bag that can be pressurized internally by a gas that is generated within the second bag. In another embodiment, the second bag is located within the first bag. When the gas is produced, the volume of the second bag increases and causes the volume of the first bag to decrease thereby dispensing the liquid under pressure. The expenses attendant with the manufacture of these concentric bags and the pressurization device that must be located in each container plus the problems of keeping these containers sterile apparently has lead to its lack of use in surgical procedures.
Similar concentric bags with an externally located pressurization device have been proposed. In one, a two-chamber container includes an inner collapsible liquid container and an outer container. Appropriate inlet and outlet means enable air to be pumped into the outer bag and the parenteral or the liquid to be stored in and dispensed from the inner bag. A reverse arrangement has also been proposed in which the air bag is dispoed inside the liquid bag. In either arrangement, the air bag is inflated to force the liquid out of the liquid bag under pressure.
Problems have been encountered with these bags, however, because the liquid bag tends to collapse and trap liquid; so the container with the trapped liquid must be thrown away before the liquid is completely used. Various solutions have been proposed. In one, the liquid chamber is centered in the air-chamber by means of flexible connecting stays. Alternatively, tubes are inserted into the liquid bag or the bag is constructed with special ribs that thereby prevent either premature closure of the bag or the entrapment of any liquid in the bag. Again, however, these special construction features tend to increase the overall costs of the bag. These containers have also not gained acceptance for use during surgical procedures.
In accordance with another approach, a container comprises juxtaposed chambers, rather than concentric bags. In one, three membranes are sealed about their peripheries to define juxtaposed liquid and pressure chambers. The container is then placed in a cardboard enclosure. When the pressure chamber is pressurized by some external means, the cardboard enclosure restricts any overall enlargement of the container. Thus, the center membrane displaces into the liquid chamber and forces the liquid out under pressure. These and other similar devices that contain juxtaposed chambers are also somewhat complex to manufacture because they are not readily produceable. This feature, as well as the need for various ancillary devices to overcome some of the foregoing problems encountered during administration of liquids, increases costs. Moreover, the need for ancillary devices, such as the foregoing cardboard enclosure, make it more difficult to handle these containers during surgical procedures.
Another possible reason for a lack of use of the prior containers during surgical procedures lies in the medical problems that can occur if the central membrane in a container having the juxtaposed chambers ruptures. If the membrane ruptures, air under pressure is admitted into the liquid chamber. If the resulting air then passes into the patient during an intravenous administration of the liquid, an embolus can result. Thus, the accepted method for delivery of liquids under pressure is to place a single chamber container with liquid into a blood pressure or other type of pressure cuff. The cuff is then inflated and contracts on the container. These pressure cuffs are cumbersome and difficult to handle. Moreover, they are difficult to sterilize. However, even with these drawbacks, the use of a pressure cuff and separate container is really the only method for delivering liquids under pressure that is widely accepted by the medical profession.
Therefore, it is an object of this invention to provide a liquid container for use in the administration of liquids to patients under pressure.
Another object of this invention is to provide a liquid container that reduces the risks of administering a liquid under pressure to a patient.
Another object of this invention is to provide a container for use as part of a pressurized liquid delivery system that is readily sterilizable.
Still another object of this invention is to provide a container for administering liquid under pressure that is easy and relatively inexpensive to manufacture.